1. Field of the Invention
This invention relates to oxygen depolarized electrochemical cells. More particularly, it relates to metal/oxygen batteries having improved sealing characteristics.
2. Prior Art
The concept of gas depolarized electrochemical cells is old in the art as evidenced by the numerous issued patents.
It is also known that gas depolarized electrochemical cells can have a "button" cell configuration and be used in a variety of applications such as hearing aids, transistor radios, watches, and miniature electronic calculators.
Patents disclosing such button cells are
Gillespie-U.K. Pat. No. 1,319,780 PA1 Jaggard-U.S. Pat No. 3,897,265 PA1 Aker-U.S. Pat. No. 3,746,580 PA1 Fangradt-U.K. Pat. No. 1,178,859
The present invention is an improvement over these zinc/air button cells.
All of the above references disclose zinc/oxygen button cells having an anode, an anode cover, a cathode assembly, a cathode can, a grommet and a separator.
The current inventors have found that cells similar to those disclosed by Gillespie and Jaggard sometimes during closure have damage to the cathode assembly thereby shorting the cell and causing leakage.
The Aker and Fangradt references disclose means to improve leakage characteristics by preventing damage to the cathode assembly and thereby preventing shorting.
The Aker cell is characterized by the periphery of the cathode assembly having a frame of non-conductive material molded around it. The frame is in contact with the grommet.
The Fangradt cell is characterized by having the non-conductive grommet hermetically bonded around the periphery of the cathode assembly.
Hence, the prior art teaches that to have a leak resistant metal/oxygen button cell, which will not short upon closure, the cathode assembly should have a non-conductive material molded around its periphery. This, however, increases the cost and difficulty of manufacture.
It would be desirable to be able to manufacture a cell having good leak resistant characteristics which did not short upon closure and would not need this measure.